Backdrop 1.30.0 now uses the token browser from the Fast Token Browser module. The Fast Token Browser module replaced the Core token browser with an AJAX powered token browser that only loaded the first level of tokens available on the page and opened additional parts of the token tree as they were requested by the user. This prevented unresponsive pages and excessive memory usage when using modules such as Entity Token.
Any site upgrading to this version of Backdrop will start using this new token browser. There is no need to enable an additional module. If your site was previously using the contributed module version of Fast Token Browser, it will be disabled with a message. You can safely remove the module folder from your installation.
The new token browser works in the same way as the original token browser in that you can select the field and the place in the field you want to insert a token, then find the token and click to insert it. However, you can also now select the token first and then select the field; with the previous token browser, this would generate a popup warning.